The hospital goes into lockdown mode when a man with a gun holds medical staff hostage. Goodwin is forced to make a tough decision. Dr. Rhodes begins to realize his…

Firehouse 51 helps Herrmann put on a school fundraiser. Carver’s troubled brother comes to town. A grateful citizen is determined to thank Brett and Severide for saving his life.

Severide and Cruz find a child’s remains inside a chimney while investigating a possible carbon monoxide leak inside a home. In other events, Casey braces for the worst in his…

Intelligence investigates a doctor who gave his patients lethal doses of chemotherapy. Roman fights a wrongful shooting investigation. The crossover starts on Chicago Fire S04E10 The Beating Heart (I) and…